The present disclosure relates to fluid filters of the type employed in pressurized fluid systems and particularly where pressurized fluid is circulated in a closed system, such as, for example, hydraulic fluid systems employed for operating hydraulic actuators and systems employing fresh water pumped under pressure. Typically, filters for pressurized fluid systems employ a vessel with a pressure chamber having an inlet and an outlet and filtering material disposed in the chamber so as to filter all of the fluid as it passes between the inlet and the outlet. It is common place to have the vessel with a removable lid on the pressure chamber so as to permit access to the filtering material for removal and replacement.
Heretofore, fluid filters of the above described type have employed granulated filtering material and filter bags for filtering of the fluid within the pressure chamber. However, eventually the filtering material becomes coated or clogged with foreign matter and flow through the system is diminished. It then becomes necessary to frequently replace the filtering material in order to continue the system in operating service. This has been particularly the case where a filter bag has been employed to provide a high degree of filtration of very fine particles of foreign matter inasmuch as the rapid buildup of particles on the surface of the filter bag has readily resulted in clogging and reduction of flow through the filter and required frequent replacement of the bag resulting in frequent and costly down time for the system. Thus, it has been desired to find a way or means of providing a high degree of filtration in the fluid system with a filter bag and yet to increase the service life of the filter bag in the pressure chamber.